1. Field of the Invention
The invention is directed to a microscope for optical detection of light radiation excited in a specimen, having a detection beam path for detecting spectral components of the light radiation in a plurality of detection channels. In the microscope, the light radiation arrives at a variable longpass filter or shortpass filter from which reflected and/or transmitted components are reflected back with a parallel offset, and any transmitted components arrive at a detector after at least one back-reflection of this kind
2. Description of Related Art
In a laser scanning microscope according to the prior art (FIG. 1), light from the light sources (lasers A-D) passes a beamsplitter (MDB), scanners, scanning optics (scanning lens), tube lens, and objective so as to impinge on the specimen in a punctiform manner. Fluorescent light, for example, is excited in the specimen and is collected through the objective and arrives at the beamsplitter again. The beamsplitter is designed in such a way that it transmits the fluorescent light based on the spectral characteristics which are altered relative to the excitation wavelength so that the detection light is focused by pinhole optics through confocal diaphragms (PH 1-4) and subsequently arrives at detectors (PMT 1-4). An emission filter (EF 1-4) is provided in front of each detector in a fluorescence microscope for suppression of the excitation light. Splitting into individual detection channels is carried out by secondary color splitters (DBS1-4). According to the prior art, different emission filters or secondary color splitters which are arranged on a wheel, for example, are swung in for adjusting the spectral characteristics of the detection channels. The illumination spot is scanned over the specimen by means of the scanner. The specimen signals are combined in a computer to form an image.
Further details on prior art can be found in “Handbook of biological confocal microscopy”, Chapter 9, editor: J. P. Pawley, Plenum Press, 1995. Various arrangements are known for spectrum-dependent influencing of detection light, all of which have disadvantages.
In DE 19835068A1, only one wavelength or one band can be adjusted by angle-dependent interference filters.
DE19835070A1 describes only a combination of graduated filters, each of which adjusts only one wavelength or one band.
In DE 102004029733A1, two bandpass filters are required. The use of even three detection channels would require four filters and four movements to be controlled and adjusted.
In DE 102006034908, there is a splitting into only two beam paths with limited flexibility if costs are to be kept low.